Why Moms Want to 'Gobble Up' Cute Babies

New moms may experience a reward response in the brain when they smell an infant.

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GE's new HDlive ultrasound creates a clear and colorful 3-D image of a fetus in utero. Parents get an excellent view of their child-to-be and doctors are able to see details that let them more accurately assess the fetus's health.

A baby laughs hysterically while his father tears up pieces of paper. But what is so funny about it?

Smells are part of a network of chemical communication signals between mother and child and they can be intense, said study author Johannes Frasnelli, a postdoctoral researcher and lecturer at the University of Montreal. (7 Ways Pregnant Women Affect Babies)

"What we have shown for the first time is that the odor of newborns, which is part of these signals, activates the neurological reward circuit in mothers," Frasnelli said in a statement. "These circuits may especially be activated when you eat while being very hungry, but also in a craving addict receiving his drug. It is in fact the sating of desire."

Frasnelli and colleagues recruited two groups of women: 15 without any kids and 15 first-time moms who had given birth three to six weeks before the experiment. (The study did not include men.)

Using functional magnetic resonance imaging (fMRI), the researchers measured the participants' brain activity as they sniffed through an olfactometer, a device that's held up to the nose to detect smells. The researchers fed the olfactometer with the odor of different infants, collected in the form of cotton undershirts worn by 18 newborns.

The women were not told what they were smelling in the experiment, and they were asked to rate how pleasant, intense and familiar each odor was.

Overall, the women in both groups rated the baby odors as weak, unfamiliar and mildly pleasant. But the moms generally had greater activity in a part of their brain linked to reward, the researchers said.